830 MICROBIOLOGY OF DISEASES OF MAN AND DOMESTIC ANIMALS 



While a great deal of popular fear exists against this disease it is 

 decidedly less infectious than pulmonary tuberculosis. Lepers have 

 unquestionably been subjected to a great deal of wholly unnecessary 

 persecution. 



Prophylactically, isolation has certainly demonstrated its value 

 and the reported increase of leprosy in certain parts of Europe has been 

 attributed to a decrease of this custom of segregation. 



PLAGUE* 



Bacterium pestis 



Epidemics have been recognized since the second century. About 

 half the population of the Roman Empire died in the sixth century. 

 An epidemic of the fourteenth century destroyed half the inhabitants 

 of Europe. In India during 1901 to 1904 about 2,000,000 died of the 

 disease. In China, in Egypt, South Africa, and in sea ports of the 

 Western hemisphere, plague has been found. 



Among animals the disease has been found chiefly in rats and 

 squirrels. Dogs may occasionally become infected. 



Four types are described, the ambulant, bubonic, septicaemic, and 

 pneumonic. The bubonic type forms three-quarters of the cases. 

 Physical and mental depression accompanied by a high fever, often with 

 a remission about the third day, occurs. Collapse may then follow with 

 death. Glandular swellings (buboes) appear in the groin and axilla 

 and these may suppurate. Haemorrhages beneath skin and mucous 

 membranes are common. The third type is a very rapid form, causing 

 death before the development of buboes. The fourth type is also a 

 short and extremely fatal form, marked by the occurrence of broncho- 

 pneumonia due to the plague bacteria. 



The bacterium of bubonic plague was described by Yersin and 

 Kitasato independently in 1893. They found it in glands and through- 

 out the body in fatal cases. 



The organism is readily grown from the buboes, the blood, and the sputum in the 

 pneumonic type, by simple inoculation of ordinary media of a slightly alkaline reac- 

 tion. The bacteria are i.5/x to i.7ju long by 0.55/1 to 0.7/1 wide with rounded ends 

 occurring singly or in pairs and short chains in exudates and sometimes in long 

 chains in broth. Involution forms, large swollen spheres, clubs, etc., are char- 



* Prepared by Edward Fidlar. 



